The fact that the mast stiffness is different in its long and short cross-sectional axis is purely a secondary issue. The primary one is of course effecting a smooth transition between the edge of the mast and the sail on the lee side of the rig. Since the sail is set at diferent angles to the boat at different points sail, the mast angle must change too, if a smooth transition is to be maintained. Also the farther off the wind you sail, the fuller the draft the sail is trimmed for and therefore the more severe the angle of mast rotation needed. The differential in bending stiffness in the fore and aft mast axis can work for or against you depending on the boat and conditions. Diamond wire/spreader adjustments are the usual ways this bending is managed, though rotation can be a complicating factor here, so that a compromise between the needed rotation and desired bend has to be reached.

Jimbo